It is said that the cell nucleolus controls the production of rRNA, that is, it produces ribossomes. The DNA lingers in the nucleolus attached to proteins from where it begins the rRNA production process. But it is also said that the ribossomes are responsible for the synthesis of proteins when they reach the citoplasm, that is their function. How can it be then that the process to produce ribossomes requires proteins that are only synthesised by the ribossomes themselves? Does this not generate a paradox?

Ok. That explains why every cell besides the original cell (or cells) are able to begin producing ribossomes. But is it explained how the process occurs with the original cell(s)? Was it by spontaneous formation?

There are several theories of origin of life and formation of cells. Just do not think that the ribosomes were there all the same for since they occurred. The proteins were probably added just later during evolution.